This proposal has as its objectives an understanding of synthesis and degradation of low molecular weight proteins. In particular, beta 2-microglobulin, an immunoglobulin-related protein, will be studied with regard to its lymphoid origins, altered synthesis in neoplastic conditions, its potential role in cell-mediated immunity, and the mechanism of its renal tubular catabolism. Differential metabolism of low molecular weight proteins will be investigated for potential value in assessing success of renal homotransplantation and in estimating degree of renal dysfunction in multiple myeloma. In addition the metabolism of two T lymphocyte antigens will be studied in a similar way.